Semiconductor current and voltage regulating circuit arrangements are well known. As time passes, the need for lower power, faster, closer tolerance and lower cost circuitry arises. Others have offered particular solutions to particular problems in this problem area. Examples of the regulator circuitry of the prior art that meet one or more of these criteria are to be found in the following U.S. patents:
______________________________________ 3,444,476 5/1969 Leidich 330/69 3,721,893 3/1973 Davis 323/4 3,868,583 2/1975 Krabbe 330/259 4,024,462 5/1977 Highnote et al 330/259 ______________________________________
And in the technical literature:
S. Ogawa, R. I. Spadavecchia and J. R. Struk; "STABILIZED REFERENCE VOLTAGE SOURCE"; IBM Technical Disclosure Bulletin; Vol. 13, No. 9; February 1971; p. 2689.
J. W. Mitchell; "Monolithic Current Source"; IBM TDB; Vol. 13, No. 12; May 1971, p. 3720;
D. Azziz; "Current-Source Scaling Circuit"; IBM TDB; Vol. 19, No. 5; October 1976, pp. 1709-10;
W. Chin; "ON-CHIP VOLTAGE REGULATOR"; IBM TDB; Vol. 19, No. 6; November 1976; pp. 2078-9.
These prior art references show circuitry having components in common with that of the invention for performing one or more of the functions that are performed by the circuitry according to the invention, but the components thereof are interconnected in different configurations and operate in different manner than the circuitry according to the invention.
The patent to Leidich shows a two-stage direct-coupled differential amplifier circuit having a feed forward (or feed back depending upon the viewpoint) path between a common load resistor for the first stage of the amplifier and for an emitter current regulating transistor in the last stage of the amplifier. This circuit arrangement corrects non-differentially and primarily for power supply variations, but the concept is probably applicable to the correction for other variations.
The patent to Davis is directed to a reference current generating circuit of the type wherein a compensating shunt drain is adjusted whereby the current flow through the current source is exactly equal to that through the load. This arrangement provides compensation without any loss due to any compensating feed back network.
The patent to Krabbe discloses balanced feedback paths for a differential amplifying circuit whereby four current sources are simultaneously and complimentary controlled for minimizing unbalance.
The patent to Highnote et al discloses a differential amplifier circuit having transistors connected in the Darlington configuration as the main amplifying devices and having precisely matched or adjusted control resistors arranged within the Darlington circuit configurations for maintaining a substantially zero direct offset current condition.
The publication to Ogawa et al discloses a stabilized reference voltage generating circuit arrangement having some similarities to the circuitry according to the invention. Here two different feedback paths are arranged for compensation but two additional current sources are required.
The arrangement of Mitchell comprises a feedback path through both sides of a single differential amplifying circuit for comparing and tracking voltages at the bases of the two transistors. If there is any difference in potential between the two voltages, feedback connection changes the base current flowing through the current transistor connected to the output emitter follower thereby bringing the voltages back into equality.
The circuits shown in the publications of Azziz and of Chin show other minor circuit configurations of the type with which the invention is concerned.
None of these references however disclose the evener circuitry according to the invention for the base current compensating circuit for the input differential amplifying circuit according to the invention hereinafter to be described.